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/* Copyright (C) 1992, 1995, 1997, 1998, 1999 Aladdin Enterprises. All rights reserved.
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This software is provided AS-IS with no warranty, either express or
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implied.
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This software is distributed under license and may not be copied,
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modified or distributed except as expressly authorized under the terms
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of the license contained in the file LICENSE in this distribution.
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For more information about licensing, please refer to
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http://www.ghostscript.com/licensing/. For information on
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commercial licensing, go to http://www.artifex.com/licensing/ or
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contact Artifex Software, Inc., 101 Lucas Valley Road #110,
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San Rafael, CA 94903, U.S.A., +1(415)492-9861.
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*/
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/* $Id: isdata.h,v 1.4 2002/02/21 22:24:53 giles Exp $ */
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/* Structure for expandable stacks of refs */
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/* Requires iref.h */
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#ifndef isdata_INCLUDED
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# define isdata_INCLUDED
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/*
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* In order to detect under- and overflow with minimum overhead, we put
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* guard elements at the top and bottom of each stack block (see idsdata.h,
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* iesdata.h, and iosdata.h for details of the individual stacks). Note that
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* the 'current' and 'next' arrays include the guard elements. See
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* istack.h for the details of stack blocks.
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*/
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/*
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* The garbage collector requires that the entire contents of every block
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* be 'clean', i.e., contain legitimate refs; we also need to ensure that
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* at GC time, pointers in unused areas of a block will not be followed
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* (since they may be dangling). We ensure this as follows:
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* - When allocating a new block, we set the entire body to nulls.
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* This is necessary because the block may be freed before the next GC,
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* and the GC must be able to scan (parse) refs even if they are free.
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* - When adding a new block to the top of the stack, we set to nulls
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* the unused area of the new next-to-top blocks.
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* - At the beginning of garbage collection, we set to nulls the unused
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* elements of the top block.
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*/
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/*
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* Define pointers into stacks. Formerly, these were short (unsegmented)
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* pointers, but this distinction is no longer needed.
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*/
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typedef ref *s_ptr;
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typedef const ref *const_s_ptr;
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/* Define an opaque allocator type. */
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#ifndef gs_ref_memory_DEFINED
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# define gs_ref_memory_DEFINED
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typedef struct gs_ref_memory_s gs_ref_memory_t;
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#endif
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/*
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* Define the state of a stack, other than the data it holds.
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* Note that the total size of a stack cannot exceed max_uint,
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* because it has to be possible to copy a stack to a PostScript array.
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*/
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#ifndef ref_stack_DEFINED
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typedef struct ref_stack_s ref_stack_t; /* also defined in idebug.h */
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# define ref_stack_DEFINED
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#endif
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/*
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* We divide the stack structure into two parts: ref_stack_params_t, which
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* is set when the stack is created and (almost) never changed after that,
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* and ref_stack_t, which changes dynamically.
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*/
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typedef struct ref_stack_params_s ref_stack_params_t;
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struct ref_stack_s {
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/* Following are updated dynamically. */
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s_ptr p; /* current top element */
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/* Following are updated when adding or deleting blocks. */
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s_ptr bot; /* bottommost valid element */
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s_ptr top; /* topmost valid element = */
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/* bot + data_size */
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ref current; /* t_array for current top block */
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uint extension_size; /* total sizes of extn. blocks */
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uint extension_used; /* total used sizes of extn. blocks */
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/* Following are updated rarely. */
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ref max_stack; /* t_integer, Max...Stack user param */
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uint requested; /* amount of last failing */
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/* push or pop request */
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uint margin; /* # of slots to leave between limit */
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/* and top */
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uint body_size; /* data_size - margin */
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/* Following are set only at initialization. */
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ref_stack_params_t *params;
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gs_ref_memory_t *memory; /* allocator for params and blocks */
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};
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#define public_st_ref_stack() /* in istack.c */\
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gs_public_st_complex_only(st_ref_stack, ref_stack_t, "ref_stack_t",\
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ref_stack_clear_marks, ref_stack_enum_ptrs, ref_stack_reloc_ptrs, 0)
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#define st_ref_stack_num_ptrs 2 /* current, params */
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#endif /* isdata_INCLUDED */
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